BBS4 and cystic kidney disease: Axonemal elongation with normal or abnormal ultrastructure has been originally reported in kidney tissues, cultured kidney-derived cells and skin-derived fibroblasts from individuals or animal models with cystic kidney diseases involving BBS4 (MIM600374), NEK8 (MIM609799, NPHP9), KIF7 (MIM611254, JBTS12), TMEM67 (MIM609884, MKS3), KIAA0556 (MIM616650, JBTS26) [38,39,40,41,42,43,44], and in fibroblasts from individuals affected with rod-cone dystrophy and hearing loss due to CEP78 mutation [45].